Create a top-level "third_party" directory

This directory now contains third_party software that is vendored into
the Servo source tree. The idea is that it would eventually hold
webrender and other crates from mozilla-central as well with a standard
patch management approach for each.

third_party/WebIDL/tests/test_const.py

@@ -0,0 +1,96 @@
+import WebIDL
+
+expected = [
+    ("::TestConsts::zero", "zero", "Byte", 0),
+    ("::TestConsts::b", "b", "Byte", -1),
+    ("::TestConsts::o", "o", "Octet", 2),
+    ("::TestConsts::s", "s", "Short", -3),
+    ("::TestConsts::us", "us", "UnsignedShort", 4),
+    ("::TestConsts::l", "l", "Long", -5),
+    ("::TestConsts::ul", "ul", "UnsignedLong", 6),
+    ("::TestConsts::ull", "ull", "UnsignedLongLong", 7),
+    ("::TestConsts::ll", "ll", "LongLong", -8),
+    ("::TestConsts::t", "t", "Boolean", True),
+    ("::TestConsts::f", "f", "Boolean", False),
+    ("::TestConsts::fl", "fl", "Float", 0.2),
+    ("::TestConsts::db", "db", "Double", 0.2),
+    ("::TestConsts::ufl", "ufl", "UnrestrictedFloat", 0.2),
+    ("::TestConsts::udb", "udb", "UnrestrictedDouble", 0.2),
+    ("::TestConsts::fli", "fli", "Float", 2),
+    ("::TestConsts::dbi", "dbi", "Double", 2),
+    ("::TestConsts::ufli", "ufli", "UnrestrictedFloat", 2),
+    ("::TestConsts::udbi", "udbi", "UnrestrictedDouble", 2),
+]
+
+
+def WebIDLTest(parser, harness):
+    parser.parse(
+        """
+        interface TestConsts {
+          const byte zero = 0;
+          const byte b = -1;
+          const octet o = 2;
+          const short s = -3;
+          const unsigned short us = 0x4;
+          const long l = -0X5;
+          const unsigned long ul = 6;
+          const unsigned long long ull = 7;
+          const long long ll = -010;
+          const boolean t = true;
+          const boolean f = false;
+          const float fl = 0.2;
+          const double db = 0.2;
+          const unrestricted float ufl = 0.2;
+          const unrestricted double udb = 0.2;
+          const float fli = 2;
+          const double dbi = 2;
+          const unrestricted float ufli = 2;
+          const unrestricted double udbi = 2;
+        };
+    """
+    )
+
+    results = parser.finish()
+
+    harness.ok(True, "TestConsts interface parsed without error.")
+    harness.check(len(results), 1, "Should be one production.")
+    iface = results[0]
+    harness.ok(isinstance(iface, WebIDL.IDLInterface), "Should be an IDLInterface")
+    harness.check(
+        iface.identifier.QName(), "::TestConsts", "Interface has the right QName"
+    )
+    harness.check(iface.identifier.name, "TestConsts", "Interface has the right name")
+    harness.check(
+        len(iface.members), len(expected), "Expect %s members" % len(expected)
+    )
+
+    for (const, (QName, name, type, value)) in zip(iface.members, expected):
+        harness.ok(isinstance(const, WebIDL.IDLConst), "Should be an IDLConst")
+        harness.ok(const.isConst(), "Const is a const")
+        harness.ok(not const.isAttr(), "Const is not an attr")
+        harness.ok(not const.isMethod(), "Const is not a method")
+        harness.check(const.identifier.QName(), QName, "Const has the right QName")
+        harness.check(const.identifier.name, name, "Const has the right name")
+        harness.check(str(const.type), type, "Const has the right type")
+        harness.ok(const.type.isPrimitive(), "All consts should be primitive")
+        harness.check(
+            str(const.value.type),
+            str(const.type),
+            "Const's value has the same type as the type",
+        )
+        harness.check(const.value.value, value, "Const value has the right value.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse(
+            """
+          interface TestConsts {
+            const boolean? zero = 0;
+          };
+        """
+        )
+        parser.finish()
+    except:
+        threw = True
+    harness.ok(threw, "Nullable types are not allowed for consts.")